It’s great that there is one office of Vietnam embassy in Sofia, Bulgaria.
Up to now, Vietnam’s embassy in Sofia is the only Vietnamese representation in Bulgaria. This office provides services of visa issuance and consular legalization among others, and also the place that Vietnamese citizens in Bulgaria should contact immediately if they lose their passport.
Regarding visa for Vietnam, in addition to embassy visa, citizens and residents of Bulgaria has an alternative way to get a Vietnam visa, which is called visa on arrival (VOA). You can see their brief below:
For details, you may also read: